Displaying child records based on parent id from URL

Question

I have one model Dataset and another one called DatasetReview, where DatasetReview has a foreign key connection to Dataset. I would like to display all of the DatasetReview models that are tied to a specific Dataset in a separate page.

I can currently view each Dataset like so: http://127.0.0.1:8000/dataset/3/ and would like to see all of the DatasetReview models for Dataset 3 like so: http://127.0.0.1:8000/dataset/3/reviews But I am unsure how to set this up.

I am not sure how to phrase this question well so I had difficulty finding other posts discussing how to do something like this. Here is my code:

urls.py:

from django.urls import path
from .views import (
    DatasetListView, 
    DatasetDetailView, 
    DatasetCreateView,
    DatasetUpdateView,
    DatasetDeleteView,
    DatasetReviewsView
    )
from . import views

urlpatterns = [
    path('', DatasetListView.as_view(), name='argo-home'),
    path('dataset/<int:pk>/', DatasetDetailView.as_view(), name='dataset-detail'),
    path('dataset/new/', DatasetCreateView.as_view(), name='dataset-create'),
    path('dataset/<int:pk>/update', DatasetUpdateView.as_view(), name='dataset-update'),
    path('dataset/<int:pk>/delete', DatasetDeleteView.as_view(), name='dataset-delete'),
    path('dataset/<int:pk>/reviews', DatasetReviewsView.as_view(), name='dataset-review'),
    path('about/', views.about, name='argo-about'),
]

views.py:

from django.shortcuts import render
from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin
from django.views.generic import (
    ListView, 
    DetailView, 
    CreateView,
    UpdateView,
    DeleteView
)
from .models import Dataset, DatasetReview

def home(request):
    context = {
        'datasets' : Dataset.objects.all(),
    }
    return render(request, 'argo/home.html', context)

class DatasetListView(ListView):
    model = Dataset
    template_name = 'argo/home.html' # <app>/<model>_<viewtype>.html
    context_object_name = 'datasets'
    ordering = ['-date_posted']

class DatasetDetailView(DetailView):
    model = Dataset

class DatasetCreateView(LoginRequiredMixin, CreateView):
    model = Dataset
    fields = ['title', 'description', 'access']

    def form_valid(self, form):
        form.instance.author = self.request.user
        form.instance.affiliation = self.request.user.affiliation
        return super().form_valid(form)

class DatasetUpdateView(LoginRequiredMixin, UserPassesTestMixin, UpdateView):
    model = Dataset
    fields = ['title', 'description']

    def form_valid(self, form):
        form.instance.author = self.request.user
        return super().form_valid(form)

    def test_func(self):
        Dataset = self.get_object()
        if self.request.user == Dataset.author:
            return True
        return False

class DatasetDeleteView(LoginRequiredMixin, UserPassesTestMixin, DeleteView):
    model = Dataset
    success_url = '/'
    
    def test_func(self):
        dataset = self.get_object()
        if self.request.user == dataset.author:
            return True
        return False
    
class DatasetReviewsView(DetailView):
    model = DatasetReview
    success_url = '/'
    
    def test_func(self):
        datasetReview = self.get_object()
        if self.request.user == datasetReview.author:
            return True
        return False

def about(request):
    return render(request, 'argo/about.html', {'title': 'About'})

models.py:

from django.db import models
from django.utils import timezone
from django.core.validators import MaxValueValidator, MinValueValidator
from django.urls import reverse
from users.models import User, Affiliation

# from django.contrib.auth.models import User

class Dataset(models.Model):
    title = models.CharField(max_length=100)
    description = models.TextField()
    date_posted = models.DateTimeField(default=timezone.now)
    affiliation = models.ForeignKey(Affiliation, on_delete=models.CASCADE, related_name='posted_datasets')
    access = models.ManyToManyField(Affiliation, related_name='available_datasets')
    author = models.ForeignKey(User, on_delete=models.CASCADE)

    def __str__(self):
        return self.title
    
    def get_absolute_url(self):
        return reverse('dataset-detail', kwargs={'pk' : self.pk})

class DatasetReview(models.Model):
    dataset = models.ForeignKey(Dataset, on_delete=models.CASCADE, related_name='reviews_obj')
    reviewer = models.ForeignKey(User, on_delete=models.CASCADE, related_name='reviews')
    comments = models.TextField()
    rating = models.FloatField(
        default=3.0,
        validators=[MaxValueValidator(5.0), MinValueValidator(1.0)]
     )

    def __str__(self):
        return self.dataset.title + ' review by ' + self.reviewer.username

    def get_absolute_url(self):
        return reverse('dataset-review', kwargs={'rpk' : self.pk})

admin.py:

from django.contrib import admin
from .models import Dataset, DatasetReview

admin.site.register(Dataset)
admin.site.register(DatasetReview)

Any tips would be super helpful, very new to django.

Answer 1

Figured this out.

The key is within class DatasetReviewsView(DetailView) in views.py. I first needed to change this inheritance to a ListView to enable what I was looking for.

Next, I just needed to provide context for what I wanted to show in my html page. This is easily done by overriding the get_context_data function, which provides the context data for templates displaying this class based view.

It makes it very easy to leverage python to provide the information I want. I could query the id of the dataset I was looking at with id = self.kwargs['pk'] (which must be included in the function parameters for get_context_data), and then I could just filter all reviews to just those with a dataset matching this id. Within the html I could then iterate over the variable num_reviews.

There is some other code that averages all the ratings to provide an overall rating as well.

class DatasetReviewsView(ListView):
    model = DatasetReview
    context_object_name = 'reviews'
    success_url = '/'

    def get_context_data(self, **kwargs):
        id = self.kwargs['pk']
        context = super(DatasetReviewsView, self).get_context_data(**kwargs)
        context['id'] = id
        context['name'] = Dataset.objects.get(pk=id).title
        context['num_reviews'] = len(DatasetReview.objects.filter(dataset=id))
        tot = 0
        for review in DatasetReview.objects.filter(dataset=id):
            tot += review.rating
        context['avg_rating'] = tot / context['num_reviews']
        return context